MathHelper: Added sgn() function. Some code cleanup.
MathHelper: Added sgn() function. Some code cleanup.

svn path=/trunk/libavg/; revision=3416

yyd01245/libavg,libavg/libavg,th3infinity/libavg,libavg/libavg,libavg/libavg,th3infinity/libavg,th3infinity/libavg,yyd01245/libavg,th3infinity/libavg,hoodie/libavg,yyd01245/libavg,scotty007/libavg,libavg/libavg,scotty007/libavg,yyd01245/libavg,hoodie/libavg,scotty007/libavg,hoodie/libavg,scotty007/libavg,hoodie/libavg